U.S. ambassador to Syria Robert Ford, who has been a vocal critic of the Assad regime's crackdown on protestors, was pelted with stones, eggs and tomatoes by government supporters as he met with an opposition leader Thursday.

The mob shouted slogans and threw tomatoes and eggs as Ford arrived at the office of the Syrian lawyer with whom he was meeting. According to the U.S. State department, the ambassador and his team barricaded themselves inside the building as the pro-Assad protestors pounded on the door, attempting to force their way in.

Secretary of State Hillary Clinton condemned the "unwarranted" attack "in the strongest possible terms. "Ambassador Ford and his aides were conducting normal embassy business and this attempt to intimidate our dipplomats through violence is wholly unjustified," said Clinton. She called Ford "a vital advocate for the legitimate aspirations of the Syrian people" who has "[put] himself on the line to bear witness to the situation on the ground in Syria."

Ford was uninjured in the attack.

Syrian security elements were late in arriving at the scene and Ford was unable to leave for an extended period of time, according to an official at the U.S. embassy. When armored embassy vehicles were finally able to pick up the diplomats, they were hit with stones and damaged.

Ford returned to the embassy without incident, escorted by Syrian police.

Soon after news of the attack circulated, rumors appeared on social networking sites alleging the Ambassador's convoy had run over a young man on his way to his meeting. A YouTube video shot by an unidentified Syrian man surfaced on the web, entitled "The American Fool Hits a Syrian Boy with His Car and Hides Like a Rat," and showing a crowd gathering outside the lawyer's office chanting pro-Assad slogans.

"Your time is coming Sarkozy," the mob chanted, threatening French president Nicolas Sarkozy, and "O Hamad and Barack, you are not up to the fight with Assad." Hamad is a reference to the Emir of Qatar, Hamad Bin Jassim Al Thani, who finances the Arab television network Al Jazeera, which has covered Syria's anti-Assad uprising extensively. Both Sarkozy and Obama have publicly criticized Syrian President Bashar al-Assad and called for reforms.

The video also showed an interview with a young man who identified himself as Firas Haydar and who alleged he was run over by the U.S. convoy. State Department spokesman Mark Toner denied allegations that Ford's convoy hit a young boy, calling it "ludicrous." He said that nobody was hit by the cars.

The U.S. embassy in Damascus released a statement that said "There is no truth" to the report that Ford's vehicle "hit a child." "The Ambassador's vehicle did not hit anyone," said the statement. "The Ambassador's vehicle was accompanied by Syrian police vehicles through the drive back to the embassy."

Syria is witnessing its seventh straight month of popular protests across the country calling for the fall of the Assad regime. Authorities have accused foreign powers, among which the United States, of orchestrating the upheaval. Ambassador Ford has been very public in supporting Syrian protests as well as defying travel restrictions and making unannounced visits to restive cities around the country.

"We go to different Syrian cities and we try to meet as many Syrians as possible, both to understand their points of view, but also to relay our message of support for their demand for freedom and for their demand for dignity," he told Christiane Amanpour of ABC News on a recent trip to Washington D.C.

Plain-clothed Syrian security elements are ubiquitous in the streets of Damascus, the Syrian capital, and have been known to swiftly stage protests emphatically in support of the President outside foreign embassies, hotels where foreign journalists stay and in response to anti-regime protests.

Hassan Abdul-Azim, the lawyer with whom Ambassador Ford was meeting, is the general coordinator of the opposition National Coordination Committee that recently held a meeting in Damascus calling for the end of violence and dialogue with authorities.

The attack on the U.S. convoy comes on the eve of what has become a weekly day of protest as demonstrators gather after well-attended Friday prayers, mosques being the only places of assembly not needing permits.